Note 7 — JOSHI

As during the moon’s circuit of the earth, the earth is also travelling on its orbit, the moon will not be between the earth and the sun again on completion of its orbit, but will have to traverse the further arc shown in the figure to come between the earth and the sun. When the moon has completed the circle of the ecliptic from the position ME, its position relative to the earth has become as NF and it has not yet come between the earth and the sun. Hence while the moon completes the circuit of the ecliptic7 in 27 days 8 hours, the time from one new moon to another is 29 days 13 hours. Hence the nakshatras will not fall on the same days in successive lunar months, and would not be suitable as names for the days. It seems that, recognising this, the ancient astronomers had to find other names. They had the lunar fortnights of 14 or 15 days from new to full and full to new moon. Hence apparently they hit on the plan of dividing these into half and regulating the influence which the sun, moon and planets were believed to exercise over events in the world by allotting one day to each of them. They knew of five planets besides the sun and moon, and by giving a day to each of them the seven-day week was formed. The term planet signifies a wanderer, and it thus perhaps seemed suitable that they should give their names to the days which would revolve endlessly in a cycle, as they themselves did in the heavens. The names of the days are: